Recombinant human tumour necrosis factor increases cytosolic free calcium in murine fibroblasts and stimulates inositol phosphate formation in L-M and arachidonic acid release in 3T3 cells.
Stimulation of murine L-M and 3T3 fibroblasts with human recombinant tumour necrosis factor (rTNF) resulted in an increase in the cytosolic free Ca2+ concentration ([Ca2+]i). In 3T3 cells rTNF also induced release and metabolization of arachidonic acid, whereas in L-M cells rTNF provoked rapid increases in the levels of inositol mono-, bis- and trisphosphates (IP1, IP2 and IP3). In these cells the Ca2+ response was also observed in Ca2+ free medium, suggesting that rTNF promotes mobilization of Ca2+ from intracellular stores. In 3T3 cells, however, Ca2+ originated from the extracellular space, since the response was abolished in medium containing 1 mM EGTA. Both rTNF-induced calcium responses were inhibited by a specific rabbit IgG antibody to rTNF but not by 1-verapamil, a blocker potential-operated calcium channels. These results suggest that increased formation of inositol phosphates, arachidonic acid release and increased cytosolic free Ca2+ are involved in the biological effects of rTNF. However, rTNF generate these signals by different mechanisms depending upon the target cell.
Bouchelouche
P N
PN
Department of Clinical Chemistry, University Hospital, Herlev, Denmark.
Bendtzen
K
K
Bak
S
S
Nielsen
O H
OH
D000818:Animals; D000906:Antibodies; D001095:Arachidonic Acids / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism*; D004731:Endotoxins / Q000494:pharmacology; D006358:Hot Temperature; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D011994:Recombinant Proteins / Q000494:pharmacology; D013050:Spectrometry, Fluorescence; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000494:pharmacology*
D000906:Antibodies; D001095:Arachidonic Acids; D004731:Endotoxins; D007295:Inositol Phosphates; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D002118:Calcium